A. Technical Field
The present invention relates to a production process for an allyl ether-based polymer. Specifically, the invention relates to a production process for an allyl ether-based polymer which is favorably used for an additive to water systems, wherein specific examples of the additive to water systems include: treating agents for water systems; detergents; water-treating agents; fiber-treating agents; scale inhibitors; and detergent builders.
B. Background Art
The scale inhibitors are used as water-treating agents for such as boilers, condensers, heat exchangers, and gas-washing towers.
Cations, such as calcium ion and magnesium ion, or anions, such as carbonate ion, bicarbonate ion, sulfite ion, and sulfate ion, and further, as the case may be, zinc ion or phosphate ion derived from anticorrosives, tend to deposit themselves in the form of scale on the following: heat transfer faces of such as boilers, condensers, and heat exchangers; surfaces of materials packed in gas-washing towers; or inner surfaces of piping. Particularly, this phenomenon badly occurs particularly in systems which involve the use of refrigerants having a high Ca concentration and a high pH and being called brine.
Such adhesion of scale brings about not only an increase in operation costs due to heat transfer effect deterioration or due to an increase in the through-flow resistance, but also abnormality of indicated values and a delay of the response speed due to the adhesion of scale to sensors of various meters such as thermometers and pH meters. In addition, such as local corrosion makes it difficult to continue normal operation. The adhered scale is so hard as not to be easy to peel off. Therefore, a great deal of costs are also needed for such as stop of operation or removal of the scale.
Thus, such as lignin-based compounds, phosphorus-based compounds, and poly((meth)acrylate salts) are conventionally used as scale inhibitors in order to inhibit the above adhesion of scale.
However, the lignin-based compounds have problems of uneven quality. In addition, as to the phosphorus-based compounds, including those which are added as the aforementioned anticorrosives, the hydrolyzed phosphate ion acts as a scale component when being high concentrated. Furthermore, if such a scale component comprising the phosphate ion is further contained in blow water and, together therewith, discharged from the system into closed water systems such as lakes, marshes, and inland seas, then the scale component causes serious environmental pollution such as red water. Of the above conventional scale inhibitors, the poly((meth)acrylate salts) are valued highly, but still easily produce scale such as zinc-based or phosphorus-based scale when being high concentrated.
Thus, in order to solve the above-mentioned problems, the present inventors proposed a scale inhibitor comprising a copolymer derived from monomer components including a (meth)acrylic acid-based monomer and an allyl ether-based monomer as an excellent scale inhibitor containing no or little phosphorus (JP-B-059640/1987).
However, a series of the present inventors"" further studies to provide a scale inhibitor which displays still higher performance have revealed that even the above polymeric scale inhibitor easily insolubilizes in boiler water systems or cooling water systems and is therefore inferior in performance as a scale inhibitor if the above polymeric scale inhibitor has low gelation resistance.
A. Object of the Invention
The present invention has been done in order to solve the above-mentioned problems, and its main object is to provide: a scale inhibitor which controls the formation of scale even in joint use with anticorrosives such as zinc-based or condensed phosphoric acid-based ones, and has so excellent gelation resistance as to be difficult to precipitate, and contains no or little phosphorus; and a polymer favorable as a raw material for this scale inhibitor; and further, similarly, a copolymer which is also applicable to an additive to water systems in fields where properties corresponding to the gelation resistance are desired.
B. Disclosure of the Invention
The present inventors diligently studied to achieve the above-mentioned object. As a result, they have found out that it is important for solution of the problems that a specific allyl ether-based monomer of the below-mentioned general formula (1) is used as the allyl ether-based monomer which is essential to the monomer component for polymerization, and that the content of a compound of the below-mentioned general formula (2) as an impurity in the monomer component in the polymerization step is not more than a specific value.
More specifically, the inventors have further found out that if a polymer has a specific structural unit derived from the aforementioned specific allyl ether-based monomer and if in this polymer the content of a dioxolane compound having an alkyl group and a haloalkyl group as substituents is not more than a specific value, then this polymer has properties suitable for various additives to water systems (e.g. treating agents, detergents, water-treating agents, fiber-treating agents, detergent builders).
In the process of the above study, the present inventors presumed various impurities in monomer components, as used for polymerization, to have an influence upon properties of a polymer obtained by polymerizing the monomer components. Furthermore, the inventors directed their attention to raw materials for producing the allyl ether-based monomer of the general formula (1) indispensable for the monomer components and, as a result, have known that the amount of a specific compound existing in the above raw materials has an influence upon properties of the polymer, and further that this compound is specifically a substituted dioxolane compound of the below-mentioned general formula (2).
A production process for an allyl ether-based polymer, according to the present invention, comprises the step of polymerizing at least one monomer component that includes an allyl ether-based monomer as an essential component, wherein: the allyl ether-based monomer is an allyl ether-based monomer of the below-mentioned general formula (1); and the content of a compound of the below-mentioned general formula (2) in the monomer component is not more than 500 ppm of the monomer component;
wherein the general formula (1) is: 
wherein:
p denotes an integer of 1 to 4;
q and r independently of each other denote 0 or an integer of 1 to 100;
R2 and R3 independently of each other denote an alkylene group with 2 to 4 carbon atoms; and
Y and Z independently of each other denote a hydroxyl group, an alkoxyl group with 1 to 4 carbon atoms, a monovalent phosphoric acid group (which may be in the form of a monovalent or divalent metal salt, an ammonium or organic amine salt, or a monoester or diester of an alkyl group with 1 to 4 carbon atoms), or a monovalent sulfonic acid group (which may be in the form of a monovalent or divalent metal salt, an ammonium or organic amine salt, or an ester of an alkyl group with 1 to 4 carbon atoms), or Y and Z are linked together and denote a divalent phosphoric or sulfonic acid group as a whole;
and wherein the general formula (2) is: 
wherein:
R4 denotes an alkylene group with 2 to 4 carbon atoms;
R5 denotes an alkyl group with 1 to 5 carbon atoms; and
X denotes a halogen.
More specifically, the compound of the above general formula (2), for example, might be an impurity in the raw materials as used when producing the above allyl ether-based monomer (I). In addition, this compound might be an impurity formed by a side reaction when producing the above allyl ether-based monomer (I).
In the production process for an allyl ether-based polymer, according to the present invention, if the content of the compound of the above general formula (2) is limited to not more than 500 ppm, then a polymer obtained from the polymerization by the process according to the present invention is enabled to have so excellent gelation resistance, for example, as never to insolubilize in boiler water systems or cooling water systems.
In addition, the above polymer is enabled to be a polymer useful for scale inhibition, which polymer can inhibit the deposition of the zinc ion or phosphate ion and thereby control the formation of scale even in joint use with anticorrosives such as zinc-based or condensed phosphoric acid-based ones, and contains no or little phosphorus because of containing no phosphorus compound and is therefore excellent in property of low environmental pollution.
In addition, similarly, the polymer obtained from the polymerization by the process according to the present invention is optimum also as a polymer having not only various properties corresponding to properties such as gelation resistance, but also other various properties (e.g. detergency, dispersibility for such as pigments and clay) desirable as an additive to water systems. Therefore, the allyl ether-based polymer according to the present invention is optimum as various additives to water systems.
The polymer, which is obtained from the polymerization by the process according to the present invention, is excellent in various properties, and is a water-soluble polymer usable for various additives to water systems.
In the production process for an allyl ether-based polymer, according to the present invention, it is favorable that the monomer components which are copolymerized include the allyl ether-based monomer of the aforementioned general formula (1) in a ratio of 1.0-95.0 weight % wherein the total of the monomer components used is 100 weight %, and more specifically that the monomer components which are copolymerized include the allyl ether-based monomer (I) of the aforementioned general formula (1) in a ratio of 1.0-95.0 weight %, a (meth)acrylic acid-based monomer (II) in a ratio of 99.0-5.0 weight %, and another copolymerizable monomer (III) in a ratio of 0-70 weight % wherein the total of these monomer components is 100 weight %.
A polymer obtained in a favorable mode for carrying out the process according to the present invention is a polymer which has an allyl ether-based monomer-derived structural unit of the below-mentioned general formula (3) in a ratio of 0.5-80 mol % to the polymer and a (meth)acrylic acid-based monomer-derived structural unit of the below-mentioned general formula (4) in a ratio of 20-99.5 mol % to the polymer,
wherein the general formula (3) is: 
wherein:
p denotes an integer of 1 to 4;
q and r independently of each other denote 0 or an integer of 1 to 100;
R2 and R3 independently of each other denote an alkylene group with 2 to 4 carbon atoms; and
Y and Z independently of each other denote a hydroxyl group, an alkoxyl group with 1 to 4 carbon atoms, a monovalent phosphoric acid group (which may be in the form of a monovalent or divalent metal salt, an ammonium or organic amine salt, or a monoester or diester of an alkyl group with 1 to 4 carbon atoms), or a monovalent sulfonic acid group (which may be in the form of a monovalent or divalent metal salt, an ammonium or organic amine salt, or an ester of an alkyl group with 1 to 4 carbon atoms), or Y and Z are linked together and denote a divalent phosphoric or sulfonic acid group as a whole;
and wherein the general formula (4) is: 
wherein:
R1 denotes an alkyl group with 1 to 12 carbon atoms or an alicyclic alkyl group; and
M denotes a metal salt;
and wherein the content of a compound of the below-mentioned general formula (2) in the polymer is not more than 500 ppm of the polymer,
wherein the general formula (2) is: 
wherein:
R4 denotes an alkylene group with 2 to 4 carbon atoms;
R5 denotes an alkyl group with 1 to 5 carbon atoms; and
X denotes a halogen.
The adoption of these constitutions, more specifically, the use of this water-soluble polymer as a scale inhibitor that is one of uses of additives to water systems, enables this polymer to have so still higher gelation resistance as to inhibit the insolubilization of this polymer to a minimum in boiler water systems or cooling water systems, and accordingly can realize scale inhibition of still higher performance.
The above polymer is enabled to be a polymer useful for scale inhibition, which polymer can inhibit the deposition of the zinc ion or phosphate ion and thereby control the formation of scale even in joint use with anticorrosives such as zinc-based or condensed phosphoric acid-based ones, and contains no or little phosphorus because of containing no phosphorus compound and is therefore excellent in property of low environmental pollution. Furthermore, this polymer is enabled to be a polymer which has so excellent gelation resistance as never to insolubilize in boiler water systems or cooling water systems.
Obtainable from the above constitutions is a scale inhibitor which can inhibit the deposition of the zinc ion or phosphate ion and thereby control the formation of scale even in joint use with anticorrosives such as zinc-based or condensed phosphoric acid-based ones, and contains no or little phosphorus because of containing no phosphorus compound and is therefore excellent in property of low environmental pollution. Furthermore, this scale inhibitor is a high performance scale inhibitor which has so excellent gelation resistance as never to insolubilize in boiler water systems or cooling water systems.
These and other objects and the advantages of the present invention will be more fully apparent from the following detailed disclosure.